Pacific Giant Salamanders in an Old and Previously Clear Cut Forest Section in Mack Creek

Introduction

Figure 1: Sampling Mack Creek Fish and Pacific Giant Salamander in Mack Creek, Oregon. Photo Credit: HJ Andrews Experimental Forest LTER

Pacific Giant Salamander…

Figure 2: Pacific Giant Salamander. Photo Credit: inPlume Design

Data and Methods

The data used in this report was collected by the H.J. Andrews Experimental Forest Long-Term Ecological Research (LTER) program. Data collection for Pacific Giant Salamanders began in 1993. The main location site is Mack Creek, which is divided into two area sections: clear cut and old growth. 500 year old coniferous forests are located in old growth areas. The area of clear cut and old growth sections are roughly 150 m reaches of stream. For more information on the sites or variables, see the metadata. The statistical tests performed were a chi-squared test, … The significance level used was 0.05. R Studio Version 1.2.5001 was used to perform all tests and to produce this report.

Figure 3: HJ Andrews Experimental Forest Map. The study site for the data, Mack Creek, is located to the east of Lookout Mountain. Photo Credit: HJ Andrews Experimental Forest LTER

Results

1. Annual Salamander Counts in Old Growth (OG) and Clear Cut (CC) sections in Mack Creek.

Annual Pacific Giant Salamander counts were compared in old growth and clear cut areas in Mack Creek. Up until 2015, clear cut areas in Mack Creek typically showed a lower count than in old growth areas. In 1995, Pacific Giant Salamander count declined by more than half than what was recorded in the previous year in 1994. However, count more than doubled from 1999 to 2000. The highest and lowest counts in both areas were 380 and 129 in old growth areas and 368 and 63 in clear cut areas.

Figure 3: Pacific Giant Salamander counts in Mack Creek for clear cut and old growth sections in 1993 to 2017. Data: Gregory S. V. 2016.

2. Annual Salamander Counts in Old Growth (OG) and Clear Cut (CC) sections in Mack Creek.

Table 1: Pacific Giant Salamander counts in channel classifications and area sections in 2017. The channel classifications are cascade, pool, and side channel. The area sections are clear cut and old growth. Proportions are in parentheses. Data: Gregory S. V. 2016.

Pacific Giant Salamander in Channels and Areas in 2017

Area Section	Cascade	Pool	Side Channel
CC	247 (67%)	31 (8%)	90 (24%)
OG	201 (63%)	45 (14%)	74 (23%)
Note:
1 CC = Clear Cut
2 OG = Old Growth

3. Finding the Difference in Where in the Channel Pacific Giant Salamanders are Located Between the Two Area Sections.

Most Pacific Giant Salamander are found in the cascade channel for both area sections (\(\sf{n_{cc}}\) = 247, \(\sf{n_{OG}}\) = 201). This is followed by the side channels (\(\sf{n_{cc}}\) = 90, \(\sf{n_{OG}}\) = 74) and pools (\(\sf{n_{cc}}\) = 31, \(\sf{n_{OG}}\) = 45) (See Table 1). There is not evidence to suggest that there is a significant effect of area sections, old growth and clear cut, on channel classification, cascade, pool, and side channel (\(\chi\)²(2) = 5.5413, p = 0.06).

Summary

References

1. Gregory S. V. 2016. Aquatic Vertebrate Population Study in Mack Creek, Andrews Experimental Forest, 1987 to present. Environmental Data Initiative. https://doi.org/10.6073/pasta/5de64af9c11579266ef20da2ff32f702. Dataset accessed 11/19/2019.